1. Field of the Invention
The invention relates to a fuel injection device for internal combustion engines, in particular a common rail injector, having a housing with an injection end, having a recess extending in the housing, having at least one axially movable valve element, which is disposed in the recess, cooperates with a valve seat, and has a pressure face, remote from the injection end, that axially defines a control chamber, having a sleeve part that radially defines the control chamber, and having at least one device that urges the sleeve part toward a first housing portion and urges the valve seat in the direction of the injection end.
2. Description of the Prior Art
One fuel injection device known on the market involves a common rail injector. In it, the control chamber is defined by an axial end face of a valve needle. Radially, the control chamber is defined by a sleeve part, in whose wall there is an inlet throttle. On the side opposite the valve needle, the control chamber is defined by a housing part in which there is an outlet throttle. The inlet throttle communicates with a high-pressure inlet, while conversely the outlet throttle communicates with a low-pressure region via a control valve. The throttling action of the inlet throttle is greater than that of the outlet throttle.
Between the sleeve part and an annular shoulder of the valve needle, a compression spring is braced. On the one hand it urges the valve needle against a valve seat in the region of the injection end, and on the other, it urges the sleeve part against the housing part. To lift the valve needle from its valve seat in the region of the injection end, the pressure in the control chamber is lowered. The normal high pressure continues to prevail at a pressure face of the valve needle. If the pressure difference is great enough, the closing force of the compression spring is overcome, causing the valve needle to move.
The object of the present invention is to refine a fuel injection device of the type described above in such a way that with it, the fuel can be injected even more precisely.
In a fuel injection device of the this type, this object is attained in that the device, which put the sleeve part against a first housing portion and the valve element in the direction of the injection end under prestressing, includes separate prestressing devices, wherein one prestressing device acts upon the valve element, and another prestressing device acts upon the sleeve part.